When using some medical imaging systems, patient alignment within the system is not a critical factor as the imaging area can be moved to a certain degree. However, recent development in the field of radiotherapy has focused on the integration of a radiotherapy system with an imaging system, such as a magnetic resonance imaging (MRI) scanner, CT scanner or PET scanner, with the goal of providing real-time (or as close to real-time as possible) feedback on the location of the patient and the target within the patient with respect to the therapeutic radiation beam. In such systems, the alignment of the patient becomes critical, as the area being imaged should be aligned as centrally as possible with respect to the treatment radiation plane.
One source of potential inaccuracy in the patient alignment is the repositioning of the bed on which the patient rests. As many imaging systems require the patient to be placed into an enclosed and confined space, often referred to as a bore, the patient must be set up for imaging and treatment outside of the bore, and then transported into the bore for the procedure to begin. The bed must therefore be movable between these two locations, and positionable to a high degree of accuracy as misalignment during set up may mean that the patient will need to be removed from the system and re-aligned before treatment can commence, wasting time and resources.
The process of moving the bed from its support outside the medical system to the bore itself requires careful alignment of the support with the treatment/imaging table of the system. This can require precise and expensive system machining to ensure the tolerances of the components involved are precise enough so as not to misalign the patient when moving from the support to the treatment/imaging table.